Hello @Localizatodo , at first we didn't really know that you were talking about API (I have just moved your topic into this API section). Unfortunately, the truth is:
"We are not allowed to provide ECMWF data to third parties, and therefore we cannot provide layers based on this data model (thunder, deg0, cloudtop, cbase, visibility, swell3, snowcover, ozone, sst and cape). We also cannot provide you with the radar layer. Everything else is included in the paid version and this Change Windy parameters tutorial will show you how to access all allowed layers (even if they are not displayed in the right menu)." – See https://api4.windy.com
I'm afraid this paragraph should also include the Waves, Wind waves and Swell (1+2+3) in the Mediterranean Sea as well as other water areas that are not covered by the 'Wavewatch 3' model. We're very sorry about that!

Hi @marienka,
unfortunately it is still not working.
In Firefox Web Console I'm getting "ReferenceError: windyInit is not defined".
Also when I try to open URL https://api4.windy.com/ the page is infinitely reloading.

Now I see (I don't know how I missed it) that there is an altitude slider at the very bottom of the selection panel that one gets if one opens the overlay selection (i.e., clicking on "Wind") in the upper right -- so I suppose I can just avoid adding this slider to the main window.
(It might still be nice to know why the above doesn't work, and if there is any way to create and open a slider on the main window. Note that Javascript console information doesn't seem to help for that -- there were no related error messages there.)